Skin bonding polymer compositions are described that include a hydrophobic polymer/hydrophilic polymer adduct and other components. These compositions can be provided as topical compositions to be applied to skin tissue. Exemplary skin bonding polymer compositions are described in U.S. Pat. No. 6,756,059, assigned to Skinvisible Pharmaceuticals, Inc. In addition, see U.S. Patent Publication No. 2002/0051797. Because of the highly hydrophobic nature of certain hydrophobic polymer/hydrophilic polymer adducts described in U.S. Pat. No. 6,756,059, ionic and water-soluble active ingredients may have difficulty being absorbed into or contained within the hydrophobic polymer/hydrophilic polymer adduct. Because a large number of active ingredients are salts, it is desirable to provide a composition that absorbs or binds ionic and water-soluble active ingredients and allows the active ingredients to be released, over time, to skin tissue. Furthermore, although certain hydrophobic polymer/hydrophilic polymer adducts can be highly hydrated, the hydrophilic compartment within certain hydrophobic polymer/hydrophilic polymer adducts may be relatively small thereby limiting the availability of the compartment to relatively small molecules such as molecules having a molecular weight of less than about 100.
In a topical delivery composition, it is often difficult to control the delivery rate of a cationic pharmaceutically active ingredient such as a cationic drug. An exemplary cationic pharmaceutically active ingredient is Imiquimod. Imiquimod is generally recognized as an immune response modifier, is considered a weak base, and is the active ingredient in Aldara® cream sold in the United States by Graceway Pharmaceuticals, LLC. Aldara® cream is often used for treatment of actinic keratosis, basal cell carcinoma, and external genital warts. Imiquimod is a potent drug with a high level of irritation. When applying a topical delivery composition containing Imiquimod, it is desirable for the composition to release Imiquimod at a rate sufficient to provide desired activity. The rate of release, however, should not be so great as to cause an undesirable side effect. For these reasons, it is desirable to control the delivery of Imiquimod. Furthermore, because Imiquimod tends to cause a high level of irritation, it is desirable to be able to use less Imiquimod while obtaining a desired level of performance.